1. Field of the Invention
The present invention relates to an inorganic ion conductive membrane, a fuel cell including the inorganic ion conductive membrane, and a method of manufacturing the same and, more particularly, to an inorganic ion conductive membrane, which is capable of obtaining a fuel cell with a stable operation in all temperature, high performance, and no leakage of fuels by manufacturing the inorganic ion conductive membrane, composed of an inorganic membrane, using an anodic oxidization reaction and applying the manufactured inorganic ion conductive membrane to the fuel cell, a fuel cell including the inorganic ion conductive membrane, and a method of manufacturing the inorganic ion conductive membrane and the fuel cell.
2. Background of the Related Art
A fuel cell is an apparatus which uses current, generated when hydrogen ions and oxygen react with each other, as a fuel. More particularly, when a fuel, such as hydrogen or hydrocarbon, is applied to one side on the basis of an ion conductive membrane and oxygen or air is applied to the other side on the basis of the ion conductive membrane, hydrogen is dissociated by a catalyst on the fuel side and divided into positrons and electrons. The dissociated positrons react with oxygen through the ion conductive membrane, thereby generating water. The generated electrons are used as power.
Fuel cells can be classified into various fuel cells according to the fuel and structure used, an operation method, and so on. From among them, in the case of a hydrogen fuel cell and a methanol fuel cell, an ion conductive membrane of polymer materials is used as the ion conductive membrane.
A typical one of the ion conductive membrane made of polymer materials is a sulfonated tetrafluoro ethylene series polymer membrane (brand name: Nafion by DuPont). Nafion has a structure in which a perfluoro vinyl ethyl group ended with a sulfonic group is attached to a polymer backbone composed of sulfonated tetrafluoro ethylene. According to analyses of a cluster-network model from among various structure models, the ion cluster of a reversed micelle structure is consecutively disposed within a fluoro carbon lattice and formed between the micelles. Accordingly, an ion channel is formed through pores each having a diameter of approximately 10×10−10 μm.
Accordingly, a pore containing an end having a similar positron conduction function can be used as the ion conductive membrane of a fuel cell. The ion conductive membrane of polymer materials has the following problems.
In case where the ion conductive membrane of polymer materials is used as an ion conductive membrane, temperature of the membrane changes according to a change in the driving temperature of a fuel cell. The diameter of an ion channel formed in the ion conductive membrane is also changed because of the characteristic of polymer having a molecular bond distance varying when temperature changes. If this phenomenon is generated, a crossover phenomenon occurs in which, when the fuel cell is operated, not only hydrogen ions, but fuels such as hydrogen or hydrocarbon invade the membrane. In the end, polarization is generated between the anode and the cathode within the fuel cell. Accordingly, there is a problem in that the performance of the fuel cell is rapidly decreased.
Furthermore, the ion conductive membrane used in the fuel cell must be strong against to mechanical shock, such as a change in the pressure, in view of its characteristic. The ion conductive membrane of polymer materials, however, is problematic in that, if used for a long time, the performance is deteriorated because it is sensitive to such physical impact.
Meanwhile, the ion conductive membrane of polymer materials physically has a direct contact with chemical materials. In view of the characteristic of polymer, such contact generates an undesirable chemical reaction. Consequently, there is a possibility that materials constituting the ion conductive membrane can be deteriorated.
Furthermore, the fuel cell must be operated in a very limited range of operating temperature in order not to damage polymer materials. Accordingly, there is a problem in that various advantages obtainable when the fuel cell is operated at high temperature have to be given up.
Accordingly, there is an urgent need for the development of an ion conductive membrane, which is capable of solving problems generated when the polymer materials are used, as an ion conductive membrane for use in a fuel cell.